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Chopin

Seiko 7S26A problem

Question

I received a 7S26A a few days ago and it was supposed to be running but when I got it it wasn't and there was a small issue with the stem/calendar changing and I said I was going to service it anyway so I didn't test it.

I stripped it all apart, and put it back together, but when I finally installed the hairspring the movement is not starting.

If I remove the hairspring and the pallet and touch lightly some of the gears, if the spring is loaded, it will start running and the hands will turn and so on. With the pallet on, if I move it left and right it seems to put in motion all the right wheels but when I install the hairspring it just won't start.

I've checked the hairspring as well as the other parts and nothing seems damaged at all.

(yes, the parts have been lubricated accordingly)

One thing that I found a little strange is the fact that with the hairspring on, if I rotate it around with the tweezers there seems to be some resistance/friction and it's not smooth easy turning. It won't return to its position unless I create more tension on the hairspring by rotating it.

Edited by Chopin

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If everything is OK until you fit the hairspring then it is the hairspring assembly. Are you sure the impulse  jewel is engaged correctly with the pallet folk horns. It might be just a mile out of beat.

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At first I thought that I didn't install it right and I kept trying but I'm pretty sure that it is.

I do know that when you don't install it correctly you can't rotate it completely on one of the sides (depending on the position of the pallet horns), right ?

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You described that there is a balance endplay issue, as in lack of it. With the pallet removed the balance (not the hairsping), will not oscillate. It can be bent pivots. even a tiny amount is enough. Also check that end stones are not installed upside down. 

Edited by jdm

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When the watch is charged, if I remove the hairspring balance and pallet and move the wheels a bit, it starts to function until the mainspring discharges.

57 minutes ago, jdm said:

With the pallet removed the balance (not the hairsping), will not oscillate.

I know that.The pallet was always there. When the hairspring balance would be installed so was the pallet so that I can check the entire functionality of the movement.

The pivot seems fine at first glance. I'll check for more details tomorrow when I have good lighting. I badly need a LED lamp...hehe.

I think I will try and install the balance without the pivot and see if there's still any friction...

Edited by Chopin

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Check the pallet fork. That is probably the problem. If the balance is okay that is. If you have an other pallet fork change to that and see if that works better. 

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Small update: I have installed just the balance, without the pallet fork, and everything seems alright so now I'll have to focus on the pallet fork... I do have a few but not sure if I have the one with the same dimensions as this one...

I'll have to check it out and try and see if I can find any damage... I checked it out before and I didn't see anything wrong...

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7005 and 7009 and such will fit i think. You will have to take a look at the parts to get the Seiko number and see if they would work. Not always you can see if the pallet fork is okay. Have seen those that look okay but still doesn't work in the movement. 

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At some point I noticed that one of the jewels from the pallet had become slightly disengaged from it's orifice but I straightened it without any issues (it seemed to go slightly under the escapement wheel and thus wouldn't fully engage). Even so they both look fine and everything seems evened out.

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You mention the watch was a non-runner. So the watch may of already been played with. With some tension on the mainspring and the gears are running freely, with the pallet fork installed, rocking it side to side and the escapement wheel is rotating, the stones are fine.
You need to ensure the balance impulse jewel aligns centre to the banking pins. You can either remove the train bridge and check visually or play with the etachron adjustment to see if there's any sign of life. But...
From what you've described I tend to agree with Jdm. Most likely a bent pivot or end-shake issue.


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Check

1. Hairspring is in between regulator pins. The earlier 7s26 (ans 7s36) had a habit of the hairspring getting dislodged.

2. Correct screw used for pallet cock. Yhe correct one has a shallow/thin head. If wrong screw used it can rub on the balance.

Hope you find the problem!

Anilv

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3 hours ago, anilv said:

1. Hairspring is in between regulator pins. The earlier 7s26 (ans 7s36) had a habit of the hairspring getting dislodged.

That is an alleged defect of the B version only, but OP has A version, which also has no "Etachron". However, all run (poorly) even with the HS dislodged from the regulator.

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Well, you're not going to believe this. I feel so embarrassed.

Apparently the second hand bent slightly and pressed against the minute hand and that is why the movement was not starting. I sorted out the hands just before going to bed and now I reinstalled the pallet fork and hairspring and it all works.

Bonus question: the oscillating weight seems to be a bit wobbly. I think the ball bearings are loosened or something like that. It makes a bit of noise and if pressed downwards it touches the metal plates beneath slightly.

Can the ball bearing for this movement's rotor be replaced ? I noticed that some are press fit and they just get replaced.

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Also, apparently the screws that I used for the pallet bridge might be incorrect as it seems to work fine without the screws in place. Either they were never right or I used them up someplace else in the movement. Not sure if possible but oh well...

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Ooops about the second hand And if wrong screws used on the pallet fork bridge and they're not flush, as "Anilv " pointed out can cause issues. If screws are being mixed up, you can always screw back in whilst stripping the movement down. I like to use multiple dishes.
1. Balance and pallet.
2. Motion works.
3. Barrel bridge etc.
4. Train .
5. Keyless works.
Looks like your Rotor has worn. Common problem. Not from any weakness in design from Seiko but years of neglect and correct maintanance. I don't believe bearings can be serviced, so if the autowind is failing, a replacement will be required.

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As a footnote hope you serviced the mainspring. I know Seiko recommend changing the barrel but people often neglect the spring and wonder why they have a low amplitude or the watch isn't performing or breakage occurs.
See pic, this movement is younger than yours, even so, it's totally dried up. Also note being Japanese, chances are it's a "Lefty"4ff5f81543246faf5a48f96ef145c775.jpg

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I don't understand how the hands became intertwined as I handle my movements very carefully and it was always sat on a movement holder. They are not the original ones but modded ones and they seem to be inferior in quality to be honest.

I have my part dishes/organizer on order but still waiting for it to arrive, sadly.

One other particularity of the movement is that in some angles it seems to stop, I think. If I wiggle it a bit it'll restart. It kind of seems as if the hairspring is weak, so to speak. Is it possible that it's misaligned (I'm talking about the 2 regulating tabs)?

Did not check the mainspring, yet but I might do that.

Edited by Chopin

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8 minutes ago, Chopin said:

One other particularity of the movement is that in some angles it seems to stop, I think. If I wiggle it a bit it'll restart. It kind of seems as if the hairspring is weak, so to speak. Is it possible that it's misaligned (I'm talking about the 2 regulating tabs)?

Did not check the mainspring, yet but I might do that.

Without pictures one can't tell about HS, however being "weak" is not enough for it too stop. First and foremost you have to check pattern and amplitude on the timegrapher. I don't know what are the "regulating tabs" you're talking about, 7S26A doesn't have any.

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Aftermarket hands are pretty useless.  While I have used them it's only as a last resort.

The rotor bearing is pressed in and should be replaceable but as the part is not available separately you would need to source a complete rotor assembly. On older watches they can be pressed in and replaced but I only do that if I want to retain the auto-wind bridge, like in this 6105 diver (also with crap aftermarket hands) in the link below.

rgds

Anilv

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5 minutes ago, anilv said:

The rotor bearing is pressed in and should be replaceable but as the part is not available separately you would need to source a complete rotor.

As mentioned above rotor bearing it is not replaceable on on the 7S26, and there is no P/N for it. Some people have tried swapping it anyway, and it hasn't worked. 

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